Self expanding stents and similar vascular intervention devices are often delivered and deployed using so called pin and pull systems. Typically, the stent is compressed between a retractable outer sheath and an inner catheter. To deploy the stent, the user has to pull the outer sheath to uncover the stent using one hand while resisting the force with the other hand on the inner catheter to maintain the position of the stent during deployment. In pin and pull systems, the user can have difficultly maintaining the inner catheter at a fixed position while simultaneously moving the outer sheath. In very difficult stent deployments, which require a large amount of force by the user, this simultaneous push and pull may lead to inaccurate stent positioning, shortening or lengthening of the stent, or possibly even damage to the stent or target vessel. Another disadvantage of pin and pull systems is that there can be a lack of control on the deployment because the force to deploy the stent decreases as more of the stent is deployed. If the user maintains the same high force during deployment, the stent may be deployed too fast for the user to control. Another potential problem relates to building up tension in the outer sheath prior to movements thereof during the deployment process. If the user pauses during the deployment and releases this built up tension, deployment errors can occur when the user resumes tension to again move the outer sheath to the deployment position fully uncovering the self explaining stent. Another concern for stent deployment systems is ensuring that friction encountered as the distal end is maneuvered to a delivery site does not cause the stent to be prematurely uncovered.
The present disclosure is directed toward one or more of the problems set forth above.